The Role Of Receptors Flashcards Preview

Biology - Unit 5 > The Role Of Receptors > Flashcards

Flashcards in The Role Of Receptors Deck (25):

Why is the pacinian corpuscle specific?

It only responds to a single type of stimulus - mechanical pressure, not heat, light or sound


How does the pacinian corpuscle produce a generator potential?

It acts as a transducer


What is the role of the transducer?

It converts the information provided by the stimulus into a form that can be understood by the body, namely the nerve impulses


What is the role of receptors?

They convert, or transduce, one form of energy to another


What is the conversion of the energy of the stimulus into a nervous impulse known as?

A generator potential


Where are the pacinian corpuscles located?

Deep in the skin and in joints, ligaments and tendons


What does the sensory neurone ending at the centre of the pacinian corpuscle have in its plasma membrane, and what is this called?

A special type of sodium channel called a stretch-mediated sodium channel


What happens when pressure is applied to the pacinian corpuscle?

It changes shape and the membrane around its neurone becomes stretched which widens the sodium channels in the membrane and sodium ions diffuse into the neurone, thereby producing a generator potential


What does the generator potential produce?

An action potential that passes along the neurone and then, via other neurones, to the central nervous system


Where are the light receptor cells of the mammalian eye found?

The retina


What are the two types of light receptors?

Rods and cones


What do rod and cone cells act as?

Transducers that convert light energy into the electrical energy of a nerve impulse


What can rod cells not do, and what does this mean?

They cannot distinguish between different wavelengths of light so they can only produce black and white images


Which light receptors are most abundant within the eyes?

Rod cells


What does the pacinian corpuscle respond to?

Changes in mechanical pressure


What do many rod cells share?

A single sensory neurone


What does the fact that many rod cells share a single sensory neurone allow them to do?

Detect light of very low intensities


How does the fact that rod cells share a single sensory neurone allow them to respond to light of very low intensities?

A certain threshold value must be exceeded before a generator potential is created in the bipolar cells that they are attached to but as a number of rod cells are are attached to a single bipolar cell, there is a much greater chance that the threshold value will be exceeded than if only a single rod cell were attached to each bipolar cell


What must be done in order to create a generator potential?

The pigment - rhodopsin, in the rod cells, must be broken down


How does the idea of breaking down rhodopsin allow rod cells to respond to low light intensities?

Low light intensity is sufficient to cause this breakdown


What is low in rod cells?

Visual acuity


What are the differences in the distribution of the rod and cone cells in the eye?

The rod cells are distributed at the periphery of the retina whereas cone cells are more concentrated at the fovea


What pigment is found in cone cells?



Why are cone cells less responsive to low light intensities?

A higher light intensity is required for the break down of Iodopsin and only a higher light intensity is therefore able to Crete a generator potential


What makes cone cells have high visual acuity?

Each cone cell has its own connection to a single bipolar cell which means the brain receives separate impulses that allow it to distinguish between two separate sources of light